Use of cable ties to bundle or secure a group of articles such as electrical wires or cables is well known. U.S. Pat. No. 3,102,311 is an early example of straps used for such purposes.
Known cable ties of conventional construction are elongate members having a head at one end, a tail at the other end and a longitudinal strap therebetween. The strap is wrapped around a bundle of articles and the tail is inserted through an aperture or passage in the head. The head of the cable tie typically includes a locking element which is engagable with the body of the strap so that when the tail is pulled through the head aperture, the locking element secures the strap body in the head.
Advances in cable tie construction have taken many forms and shapes. However, since the initial introduction of cable ties, the development of self-locking devices carried in the cable tie head have taken basically two divergent paths.
One approach has been to form an integral one-piece plastic cable tie where the locking element is formed integrally with the head of the cable tie. An example of an integrally formed one-piece cable tie is shown in U.S. Pat. No. 3,965,538. One advantage of such an integrally formed one-piece cable tie is that the tie exhibits relatively low insertion force. That is, it is relatively easy to insert the tail of the tie through the head aperture. An integrally formed flexibly supported pawl forming the locking element facilitates such ease of insertion.
A second distinct approach used to form cable ties has been the use of a cable tie having a metallic barb embedded into the cable tie head at an acute angle with respect to the inserted tail. The metal barb permits insertion of the cable tie strap through the head aperture but bites into the strap upon an attempt to withdraw the strap therefrom. An example of a cable tie having such construction is shown and described in U.S. Pat. No. 3,186,047. As the metal barb of the cable tie actually bites into the inserted tail preventing withdrawal, cable ties of this construction exhibit high long-term pull-out resistance. This results in the cable tie having good loop tensile strength over time which is an important criteria in the selection and use of cable ties.
The cable tie art has also seen attempts to obtain the benefits of both an integrally molded one-piece cable tie and those of the two-piece cable tie having an embedded metallic barb. One such attempt at a multiple piece cable tie is seen in U.S. Pat. No. 5,121,524 where the cable tie is formed to have a head including a hingedly mounted pawl which holds a metallic barb therein. The pawl is flexibly rotatably movable within the head upon insertion of the strap. The metal barb supported by the pawl bites into the strap upon attempted withdrawal of the strap. A further example of the combination of the two technologies is shown in U.S. Pat. No. 5,193,251 where the head of the cable tie includes a metallic barb supported on a cantilevered platform. The platform is deflectable upon insertion of the strap through the aperture to permit ease of passage therethrough. The barb is positioned for biting insertion into the strap upon an attempt to withdraw the strap from the aperture.
While the cable ties shown in each of these patents attempts to provide the advantages of both types of cable tie technology, there is still a need to provide a cable tie which exhibits high long-term loop tensile strength as well as low strap insertion force.